A method and system for ensuring the secure authentication of transactions over a communication network using a validation code 40, wherein the user submits information over a communication terminal and submitting validation code 40 for authentication allows the transaction to be completed, the system comprised of: a substantially transparent alphanumeric cipher card 10 associated with the user information, wherein cipher card 10 contains rows and columns of random alphanumeric characters; and an authentication module for providing validation code 40 to the user whereby a color grid 20 is generated to be displayed on a user terminal, wherein the cells of color grid 20 are randomly filled with one of a plurality of colors and the design of color grid 20 is adapted to cipher card 10 such that upon positioning alphanumeric cipher card 10 over color grid 20, the user can deduce a validation code 40.